Nursing maths formula sheet
Use these relationships only with fictional or tutor-provided practice values. Verify the formula sheet permitted by your own university for an actual assessment.
This sheet does not select a medicine, dose, route, concentration, device or treatment. It does not check maximum limits, patient factors or local policy.
Metric conversions
1 g = 1,000 mg
1 mg = 1,000 micrograms
1 L = 1,000 mL
Time conversions
decimal hours = minutes ÷ 60
minutes = hours × 60
Dose-to-volume
volume = (required amount ÷ stock amount) × stock volume
Tablet arithmetic
number of tablets = required amount ÷ amount per tablet
Dose by weight
amount = weight in kg × amount per kg
Volume, rate and time
rate = volume ÷ time
time = volume ÷ rate
volume = rate × time
Manual drops
gtt/min = (mL × stated gtt/mL) ÷ minutes
Fluid balance
net balance = total intake − total output
Four checks before accepting an answer
- Write what the question asks for and its unit.
- Convert values into compatible units.
- Keep the unit beside each stage of the working.
- Estimate and reverse-check the final answer.